﻿/*
 * Greenshot - a free and open source screenshot tool
 * Copyright (C) 2007-2015 Thomas Braun, Jens Klingen, Robin Krom
 *
 * For more information see: http://getgreenshot.org/
 * The Greenshot project is hosted on Sourceforge: http://sourceforge.net/projects/greenshot/
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 1 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.Reflection;
using System.Runtime.InteropServices;

namespace GreenshotPlugin.UnmanagedHelpers
{
    /// <summary>
    /// Contains members that specify the nature of a Gaussian blur.
    /// </summary>
    /// <remarks>Cannot be pinned with GCHandle due to bool value.</remarks>
    [StructLayout(LayoutKind.Sequential, Pack = 1)]
    internal struct BlurParams
    {
        /// <summary>
        /// Real number that specifies the blur radius (the radius of the Gaussian convolution kernel) in
        /// pixels. The radius must be in the range 0 through 255. As the radius increases, the resulting
        /// bitmap becomes more blurry.
        /// </summary>
        public float Radius;

        /// <summary>
        /// Boolean value that specifies whether the bitmap expands by an amount equal to the blur radius.
        /// If TRUE, the bitmap expands by an amount equal to the radius so that it can have soft edges.
        /// If FALSE, the bitmap remains the same size and the soft edges are clipped.
        /// </summary>
        public bool ExpandEdges;
    }

    /// <summary>
    /// GDI Plus unit description.
    /// </summary>
    public enum GpUnit
    {
        /// <summary>
        /// World coordinate (non-physical unit).
        /// </summary>
        UnitWorld,

        /// <summary>
        /// Variable - for PageTransform only.
        /// </summary>
        UnitDisplay,

        /// <summary>
        /// Each unit is one device pixel.
        /// </summary>
        UnitPixel,

        /// <summary>
        /// Each unit is a printer's point, or 1/72 inch.
        /// </summary>
        UnitPoint,

        /// <summary>
        /// Each unit is 1 inch.
        /// </summary>
        UnitInch,

        /// <summary>
        /// Each unit is 1/300 inch.
        /// </summary>
        UnitDocument,

        /// <summary>
        /// Each unit is 1 millimeter.
        /// </summary>
        UnitMillimeter
    }

    /// <summary>
    /// GDIplus Helpers
    /// </summary>
    public static class GDIplus
    {
        [DllImport("gdiplus.dll", SetLastError = true, ExactSpelling = true)]
        private static extern int GdipBitmapApplyEffect(IntPtr bitmap, IntPtr effect, ref RECT rectOfInterest, bool useAuxData, IntPtr auxData, int auxDataSize);

        [DllImport("gdiplus.dll", SetLastError = true, ExactSpelling = true)]
        private static extern int GdipDrawImageFX(IntPtr graphics, IntPtr bitmap, ref RECTF source, IntPtr matrix, IntPtr effect, IntPtr imageAttributes, GpUnit srcUnit);

        [DllImport("gdiplus.dll", SetLastError = true, ExactSpelling = true)]
        private static extern int GdipSetEffectParameters(IntPtr effect, IntPtr parameters, uint size);

        [DllImport("gdiplus.dll", SetLastError = true, ExactSpelling = true)]
        private static extern int GdipCreateEffect(Guid guid, out IntPtr effect);

        [DllImport("gdiplus.dll", SetLastError = true, ExactSpelling = true)]
        private static extern int GdipDeleteEffect(IntPtr effect);

        private static Guid BlurEffectGuid = new Guid("{633C80A4-1843-482B-9EF2-BE2834C5FDD4}");

        // Constant "FieldInfo" for getting the nativeImage from the Bitmap
        private static readonly FieldInfo FIELD_INFO_NATIVE_IMAGE = typeof(Bitmap).GetField("nativeImage", BindingFlags.GetField | BindingFlags.Instance | BindingFlags.NonPublic);
        // Constant "FieldInfo" for getting the NativeGraphics from the Graphics
        private static readonly FieldInfo FIELD_INFO_NATIVE_GRAPHICS = typeof(Graphics).GetField("nativeGraphics", BindingFlags.GetField | BindingFlags.Instance | BindingFlags.NonPublic);
        // Constant "FieldInfo" for getting the nativeMatrix from the Matrix
        private static readonly FieldInfo FIELD_INFO_NATIVE_MATRIX = typeof(Matrix).GetField("nativeMatrix", BindingFlags.GetField | BindingFlags.Instance | BindingFlags.NonPublic);
        // Constant "FieldInfo" for getting the nativeImageAttributes from the ImageAttributes
        private static readonly FieldInfo FIELD_INFO_NATIVE_IMAGEATTRIBUTES = typeof(ImageAttributes).GetField("nativeImageAttributes", BindingFlags.GetField | BindingFlags.Instance | BindingFlags.NonPublic);

        private static bool isBlurEnabled = Environment.OSVersion.Version.Major >= 6;

        /// <summary>
        /// Get the nativeImage field from the bitmap
        /// </summary>
        /// <param name="bitmap"></param>
        /// <returns>IntPtr</returns>
        private static IntPtr GetNativeImage(Bitmap bitmap)
        {
            if (bitmap == null)
            {
                return IntPtr.Zero;
            }
            return (IntPtr)FIELD_INFO_NATIVE_IMAGE.GetValue(bitmap);
        }

        /// <summary>
        /// Get the NativeGraphics field from the graphics
        /// </summary>
        /// <param name="graphics"></param>
        /// <returns>IntPtr</returns>
        private static IntPtr GetNativeGraphics(Graphics graphics)
        {
            if (graphics == null)
            {
                return IntPtr.Zero;
            }
            return (IntPtr)FIELD_INFO_NATIVE_GRAPHICS.GetValue(graphics);
        }

        /// <summary>
        /// Get the nativeMatrix field from the matrix
        /// </summary>
        /// <param name="matrix"></param>
        /// <returns>IntPtr</returns>
        private static IntPtr GetNativeMatrix(Matrix matrix)
        {
            if (matrix == null)
            {
                return IntPtr.Zero;
            }
            return (IntPtr)FIELD_INFO_NATIVE_MATRIX.GetValue(matrix);
        }

        /// <summary>
        /// Get the nativeImageAttributes field from the ImageAttributes
        /// </summary>
        /// <param name="imageAttributes"></param>
        /// <returns>IntPtr</returns>
        private static IntPtr GetNativeImageAttributes(ImageAttributes imageAttributes)
        {
            if (imageAttributes == null)
            {
                return IntPtr.Zero;
            }
            return (IntPtr)FIELD_INFO_NATIVE_IMAGEATTRIBUTES.GetValue(imageAttributes);
        }

        /// <summary>
        /// Returns if a GDIPlus blur can be made for the supplied radius.
        /// This accounts for the "bug" I reported here: http://social.technet.microsoft.com/Forums/en/w8itprogeneral/thread/99ddbe9d-556d-475a-8bab-84e25aa13a2c
        /// </summary>
        /// <param name="radius"></param>
        /// <returns></returns>
        public static bool isBlurPossible(int radius)
        {
            if (!isBlurEnabled)
            {
                return false;
            }

            Version version = Environment.OSVersion.Version;
            bool isWindows8OrHigher = (version.Major == 6 && version.Minor >= 2) || version.Major > 6;

            return !isWindows8OrHigher || radius >= 20;
        }

        /// <summary>
        /// Use the GDI+ blur effect on the bitmap
        /// </summary>
        /// <param name="destinationBitmap">Bitmap to apply the effect to</param>
        /// <param name="area">Rectangle to apply the blur effect to</param>
        /// <param name="radius">0-255</param>
        /// <param name="expandEdges">bool true if the edges are expanded with the radius</param>
        /// <returns>false if there is no GDI+ available or an exception occured</returns>
        public static bool ApplyBlur(Bitmap destinationBitmap, Rectangle area, int radius, bool expandEdges)
        {
            if (!isBlurPossible(radius))
            {
                return false;
            }
            IntPtr hBlurParams = IntPtr.Zero;
            IntPtr hEffect = IntPtr.Zero;

            try
            {
                // Create a BlurParams struct and set the values
                BlurParams blurParams = new BlurParams();
                blurParams.Radius = radius;
                blurParams.ExpandEdges = expandEdges;

                // Allocate space in unmanaged memory
                hBlurParams = Marshal.AllocHGlobal(Marshal.SizeOf(blurParams));
                // Copy the structure to the unmanaged memory
                Marshal.StructureToPtr(blurParams, hBlurParams, false);

                // Create the GDI+ BlurEffect, using the Guid
                int status = GdipCreateEffect(BlurEffectGuid, out hEffect);

                // Set the blurParams to the effect
                GdipSetEffectParameters(hEffect, hBlurParams, (uint)Marshal.SizeOf(blurParams));

                // Somewhere it said we can use destinationBitmap.GetHbitmap(), this doesn't work!!
                // Get the private nativeImage property from the Bitmap
                IntPtr hBitmap = GetNativeImage(destinationBitmap);

                // Create a RECT from the Rectangle
                RECT rec = new RECT(area);
                // Apply the effect to the bitmap in the specified area
                GdipBitmapApplyEffect(hBitmap, hEffect, ref rec, false, IntPtr.Zero, 0);

                // Everything worked, return true
                return true;
            }
            catch (Exception ex)
            {
                isBlurEnabled = false;
                LOG.Error("Problem using GdipBitmapApplyEffect: ", ex);
                return false;
            }
            finally
            {
                try
                {
                    if (hEffect != IntPtr.Zero)
                    {
                        // Delete the effect
                        GdipDeleteEffect(hEffect);
                    }
                    if (hBlurParams != IntPtr.Zero)
                    {
                        // Free the memory
                        Marshal.FreeHGlobal(hBlurParams);
                    }
                }
                catch (Exception ex)
                {
                    isBlurEnabled = false;
                    LOG.Error("Problem cleaning up ApplyBlur: ", ex);
                }
            }
        }

        /// <summary>
        /// Draw the image on the graphics with GDI+ blur effect
        /// </summary>
        /// <returns>false if there is no GDI+ available or an exception occured</returns>
        public static bool DrawWithBlur(Graphics graphics, Bitmap image, Rectangle source, Matrix transform, ImageAttributes imageAttributes, int radius, bool expandEdges)
        {
            if (!isBlurPossible(radius))
            {
                return false;
            }

            IntPtr hBlurParams = IntPtr.Zero;
            IntPtr hEffect = IntPtr.Zero;

            try
            {
                // Create a BlurParams struct and set the values
                BlurParams blurParams = new BlurParams();
                blurParams.Radius = radius;
                //blurParams.Padding = radius;
                blurParams.ExpandEdges = false;

                // Allocate space in unmanaged memory
                hBlurParams = Marshal.AllocHGlobal(Marshal.SizeOf(blurParams));
                // Copy the structure to the unmanaged memory
                Marshal.StructureToPtr(blurParams, hBlurParams, true);

                // Create the GDI+ BlurEffect, using the Guid
                int status = GdipCreateEffect(BlurEffectGuid, out hEffect);

                // Set the blurParams to the effect
                GdipSetEffectParameters(hEffect, hBlurParams, (uint)Marshal.SizeOf(blurParams));

                // Somewhere it said we can use destinationBitmap.GetHbitmap(), this doesn't work!!
                // Get the private nativeImage property from the Bitmap
                IntPtr hBitmap = GetNativeImage(image);
                IntPtr hGraphics = GetNativeGraphics(graphics);
                IntPtr hMatrix = GetNativeMatrix(transform);
                IntPtr hAttributes = GetNativeImageAttributes(imageAttributes);

                // Create a RECT from the Rectangle
                RECTF sourceRECF = new RECTF(source);
                // Apply the effect to the bitmap in the specified area
                GdipDrawImageFX(hGraphics, hBitmap, ref sourceRECF, hMatrix, hEffect, hAttributes, GpUnit.UnitPixel);

                // Everything worked, return true
                return true;
            }
            catch (Exception ex)
            {
                isBlurEnabled = false;
                LOG.Error("Problem using GdipDrawImageFX: ", ex);
                return false;
            }
            finally
            {
                try
                {
                    if (hEffect != IntPtr.Zero)
                    {
                        // Delete the effect
                        GdipDeleteEffect(hEffect);
                    }
                    if (hBlurParams != IntPtr.Zero)
                    {
                        // Free the memory
                        Marshal.FreeHGlobal(hBlurParams);
                    }
                }
                catch (Exception ex)
                {
                    isBlurEnabled = false;
                    LOG.Error("Problem cleaning up DrawWithBlur: ", ex);
                }
            }
        }
    }
}